Urea-based pressure sensitive adhesives

ABSTRACT

Non-silicone urea-based adhesives are disclosed which are prepared by the polymerization of reactive oligomers with the general formula X—B—X, where X is an ethylenically unsaturated group and B is a unit free of silicone and containing urea groups. The reactive oligomers can be prepared from polyamines through chain extension reactions using diaryl carbonates followed by capping reactions. Adhesive articles, including optical adhesive articles may be prepared using the disclosed non-silicone urea-based adhesives.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to the field of adhesives,specifically to the field of pressure sensitive adhesives that arenon-silicone urea-based.

BACKGROUND

Adhesives have been used for a variety of marking, holding, protecting,sealing and masking purposes. Adhesive tapes generally comprise abacking, or substrate, and an adhesive. One type of adhesive, a pressuresensitive adhesive, is particularly preferred for many applications.

Pressure sensitive adhesives are well known to one of ordinary skill inthe art to possess certain properties at room temperature including thefollowing: (1) aggressive and permanent tack, (2) adherence with no morethan finger pressure, (3) sufficient ability to hold onto an adherend,and (4) sufficient cohesive strength to be removed cleanly from theadherend. Materials that have been found to function well as pressuresensitive adhesives are polymers designed and formulated to exhibit therequisite viscoelastic properties resulting in a desired balance oftack, peel adhesion, and shear strength. The most commonly used polymersfor preparation of pressure sensitive adhesives are natural rubber,synthetic rubbers (e.g., styrene/butadiene copolymers (SBR) andstyrene/isoprene/styrene (SIS) block copolymers), various (meth)acrylate(e.g., acrylate and methacrylate) copolymers and silicones. Each ofthese classes of materials has advantages and disadvantages.

SUMMARY

The use of adhesives, especially pressure sensitive adhesives, in areassuch as the medical, electronic and optical industries is increasing.The requirements of these industries place additional demands upon thepressure sensitive adhesive beyond the traditional properties of tack,peel adhesion and shear strength. New classes of materials are desirableto meet the increasingly demanding performance requirements for pressuresensitive adhesives.

A class of non-silicone urea-based adhesives, specifically pressuresensitive adhesives, are disclosed. These urea based adhesives areprepared from curable non-silicone urea-based reactive oligomers. Thereactive oligomers contain free radically polymerizable groups.

In some embodiments the disclosure includes an adhesive comprising acured mixture containing at least one X—B—X reactive oligomer, in whichX comprises an ethylenically unsaturated group, and B comprises anon-silicone segmented urea-based unit. The adhesive may also includeother ethylenically unsaturated monomers. The urea-based unit maycontain polyoxyalkylene groups.

In other embodiments the disclosure includes a polymerizable reactiveoligomer comprising the structure X—B—X, in which X comprises anethylenically unsaturated group and B comprises a non-silicone segmentedurea-based unit. The reactive oligomers may be prepared from polyaminesthrough chain extension and/or capping reactions.

In some embodiments the disclosure includes a curable reaction mixturecomprising at least one X—B—X reactive oligomer, in which X comprises anethylenically unsaturated group, and B comprises a non-siliconesegmented urea-based unit; and an initiator. The curable reactionmixture may also include other ethylenically unsaturated monomers.

Also disclosed are methods of preparing an adhesive comprising providinga curable composition comprising at least one X—B—X reactive oligomer,in which X comprises an ethylenically unsaturated group, and B comprisesa non-silicone segmented urea-based unit, and an initiator; and curingthe curable composition.

Additionally, adhesive articles are disclosed. Among the adhesivearticles disclosed are adhesive articles comprising a pressure sensitiveadhesive comprising the cured reaction product of at least one X—B—Xreactive oligomer, in which X comprises an ethylenically unsaturatedgroup, and B comprises a non-silicone segmented urea-based unit; and asubstrate. In some embodiments the substrate is an optical substrate.Some articles also include a second substrate.

DETAILED DESCRIPTION

Non-silicone urea-based adhesives, especially non-silicone urea-basedpressure sensitive adhesives, are prepared by the free radicalpolymerization of non-silicone containing urea-based reactive oligomers.The reactive oligomers are prepared by end-capping non-siliconesegmented urea-based polyamines with ethylenically unsaturated groups.The non-silicone urea-based polyamines are prepared by chain extensionof polyamines with carbonates. In some embodiments the non-siliconeurea-based adhesives contain polyoxyalkylene (polyether) groups.

The term “adhesive” as used herein refers to polymeric compositionsuseful to adhere together two adherends. Examples of adhesives are heatactivated adhesives and pressure sensitive adhesives.

Heat activated adhesives are non-tacky at room temperature but becometacky and capable of bonding to a substrate at elevated temperatures.These adhesives usually have a Tg (glass transition temperature) ormelting point (Tm) above room temperature. When the temperature iselevated above the Tg or Tm, the storage modulus usually decreases andthe adhesive becomes tacky.

Pressure sensitive adhesive compositions are well known to those ofordinary skill in the art to possess properties including the following:(1) aggressive and permanent tack, (2) adherence with no more thanfinger pressure, (3) sufficient ability to hold onto an adherend, and(4) sufficient cohesive strength to be cleanly removable from theadherend. Materials that have been found to function well as pressuresensitive adhesives are polymers designed and formulated to exhibit therequisite viscoelastic properties resulting in a desired balance oftack, peel adhesion, and shear holding power. Obtaining the properbalance of properties is not a simple process.

The term “non-silicone” as used herein refers to segmented copolymers orunits of segmented copolymers that are free of silicone units. The termssilicone or siloxane are used interchangeably and refer to units withdialkyl or diaryl siloxane (—SiR₂O—) repeating units.

The term “urea-based” as used herein refers to macromolecules that aresegmented copolymers which contain at least one urea linkage.

The term “segmented copolymer” refers to a copolymer of linked segments,each segment constitutes primarily a single structural unit or type ofrepeating unit. For example, a polyoxyalkylene segmented copolymer mayhave the following structure:

—CH₂CH₂(OCH₂CH₂)_(n)OCH₂CH₂-A-CH₂CH₂(OCH₂CH₂)_(n)OCH₂CH₂—

where A is the linkage between the 2 polyoxyalkylene segments.

The term “reactive oligomer” as used herein refers to a macromoleculewhich contains terminal free radically polymerizable groups and at least2 segments which are linked. “Urea-based reactive oligomers” aremacromolecules which contain terminal free radical polymerizable groupsand at least 2 segments which are linked by urea linkages.

The term “alkyl” refers to a monovalent group that is a radical of analkane, which is a saturated hydrocarbon. The alkyl can be linear,branched, cyclic, or combinations thereof and typically has 1 to 20carbon atoms. In some embodiments, the alkyl group contains 1 to 18, 1to 12, 1 to 10, 1 to 8, 1 to 6, or 1 to 4 carbon atoms. Examples ofalkyl groups include, but are not limited to, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, n-hexyl, cyclohexyl,n-heptyl, n-octyl, and ethylhexyl.

The term “aryl” refers to a monovalent group that is aromatic andcarbocyclic. The aryl can have one to five rings that are connected toor fused to the aromatic ring. The other ring structures can bearomatic, non-aromatic, or combinations thereof. Examples of aryl groupsinclude, but are not limited to, phenyl, biphenyl, terphenyl, anthryl,naphthyl, acenaphthyl, anthraquinonyl, phenanthryl, anthracenyl,pyrenyl, perylenyl, and fluorenyl.

The term “alkylene” refers to a divalent group that is a radical of analkane. The alkylene can be straight-chained, branched, cyclic, orcombinations thereof. The alkylene often has 1 to 20 carbon atoms. Insome embodiments, the alkylene contains 1 to 18, 1 to 12, 1 to 10, 1 to8, 1 to 6, or 1 to 4 carbon atoms. The radical centers of the alkylenecan be on the same carbon atom (i.e., an alkylidene) or on differentcarbon atoms.

The term “heteroalkylene” refers to a divalent group that includes atleast two alkylene groups connected by a thio, oxy, or —NR— where R isalkyl. The heteroalkylene can be linear, branched, cyclic, substitutedwith alkyl groups, or combinations thereof. Some heteroalkylenes arepoloxyyalkylenes where the heteroatom is oxygen such as for example,—CH₂CH₂(OCH₂CH₂)_(n)OCH₂CH₂—.

The term “arylene” refers to a divalent group that is carbocyclic andaromatic. The group has one to five rings that are connected, fused, orcombinations thereof. The other rings can be aromatic, non-aromatic, orcombinations thereof. In some embodiments, the arylene group has up to 5rings, up to 4 rings, up to 3 rings, up to 2 rings, or one aromaticring. For example, the arylene group can be phenylene.

The term “heteroarylene” refers to a divalent group that is carbocyclicand aromatic and contains heteroatoms such as sulfur, oxygen, nitrogenor halogens such as fluorine, chlorine, bromine or iodine.

The term “aralkylene” refers to a divalent group of formula—R^(a)—Ar^(a)— where R^(a) is an alkylene and Ar^(a) is an arylene(i.e., an alkylene is bonded to an arylene).

The term “(meth)acrylate” refers to monomeric acrylic or methacrylicesters of alcohols. Acrylate and methacrylate monomers are referred tocollectively herein as “(meth)acrylate” monomers.

The terms “free radically polymerizable” and “ethylenically unsaturated”are used interchangeably and refer to a reactive group which contains acarbon-carbon double bond which is able to be polymerized via a freeradical polymerization mechanism.

Unless otherwise indicated, “optically clear” refers to an adhesive orarticle that has a high light transmittance over at least a portion ofthe visible light spectrum (about 400 to about 700 nm), and thatexhibits low haze.

Unless otherwise indicated, “self wetting” refers to an adhesive whichis very soft and conformable and is able to be applied with very lowlamination pressure. Such adhesives exhibit spontaneous wet out tosurfaces.

Unless otherwise indicated, “removable” refers to an adhesive that hasrelatively low initial adhesion (permitting temporary removability fromand repositionability on a substrate after application), with a buildingof adhesion over time (to form a sufficiently strong bond), but remains“removable” i.e. the adhesion does not build beyond the point where itis permanently cleanly removable from the substrate.

Non-silicone urea-based polyamines are used to prepare the non-siliconeurea-based adhesives. The preparation of non-silicone urea-basedpolyamines may be achieved through the reaction of polyamines withcarbonates. A wide variety of different types of polyamines may be used.In some embodiments the polyamines are polyoxyalkylene polyamines. Suchpolyamines are also sometimes referred to as polyether polyamines.

The polyoxyalkylene polyamine may be, for example, a polyoxyethylenepolyamine, polyoxypropylene polyamine, polyoxytetramethylene polyamine,or mixtures thereof. Polyoxyethylene polyamine may be especially usefulwhen preparing the adhesive for medical applications, for example, wherehigh vapor transfer medium may be desirable.

Many polyoxyalkylene polyamines are commercially available. For example,polyoxyalkylene diamines are available under trade designations such asD-230, D-400, D-2000, D-4000, DU-700, ED-2001 and EDR-148 (availablefrom Huntsman Chemical; Houston, Tex. under the family trade designationJEFFAMINE). Polyoxyalkylene triamines are available under tradedesignations such as T-3000 and T-5000 (available from HuntsmanChemical; Houston, Tex.).

A variety of different carbonates may be reacted with the polyamine togive the non-silicone urea-based polyamine. Suitable carbonates includealkyl, aryl and mixed alkyl-aryl carbonates. Examples include carbonatessuch as ethylene carbonate, 1,2- or 1,3-propylene carbonate, diphenylcarbonate, ditolyl carbonate, dinaphthyl carbonate, ethyl phenylcarbonate, dibenzyl carbonate, dimethyl carbonate, diethyl carbonate,dipropyl carbonate, dibutyl carbonate, dihexyl carbonate, and the like.In some embodiments the carbonate is a diaryl carbonate, such as forexample, diphenyl carbonate.

In some embodiments the polyoxyalkylene polyamine is a polyoxyalkylenediamine which yields a non-silicone urea-based diamine. In one specificembodiment, the reaction of 4 equivalents of polyoxyalkylene diaminewith 3 equivalent of carbonate yields a chain-extended, non-siliconeurea-based diamine and 6 equivalents of an alcohol byproduct, as shownin reaction scheme I below (R in this case is an aryl group such asphenyl and n is an integer of 30-40):

A reaction scheme such as shown for Reaction Scheme I is sometimescalled a “chain extension reaction” because the starting material is adiamine and the product is a longer chain diamine. The chain extensionreaction shown in Reaction Scheme I can be used to give higher or lowermolecular weight by varying the equivalents of diamine and carbonateused.

The non-silicone urea-based reactive oligomers of this disclosure havethe general structure X—B—X. In this structure the B unit is anon-silicone urea-based group and the X groups are ethylenicallyunsaturated groups.

The B unit is non-silicone and contains at least one urea group and mayalso contain a variety of other groups such as urethane groups, amidegroups, ether groups, carbonyl groups, ester groups, alkylene groups,heteroalkylene groups, arylene groups, heteroarylene groups, aralkylenegroups, or combinations thereof. The composition of the B unit resultsfrom the choice of precursor compounds used to form the X—B—X reactiveoligomer.

To prepare the non-silicone urea-based reactive oligomers of thisdisclosure, two different reaction pathways may be used. In the firstreaction pathway a non-silicone urea-based polyamine such as anon-silicone urea-based diamine is reacted with an X—Z compound. The Zgroup of the X—Z compound is an amine reactive group and the X group isan ethylenically unsaturated group. A variety of Z groups are useful forthis reaction pathway including carboxylic acids, isocyantes, epoxies,azlactones and anhydrides. The X group contains an ethylenicallyunsaturated group (i.e. a carbon-carbon double bond) and is linked tothe Z group. The link between the X and Z groups may be a single bond orit may be a linking group. The linking group may be an alkylene group, aheteroalkylene group, an arylene group, a heteroarylene group, anaralkylene group, or a combination thereof.

Examples of X—Z compounds include isocyanatoethyl methacrylate, alkenylazlactones such as vinyl dimethyl azlactone and isopropenyl dimethylazlactone, m-isopropenyl-α,α-dimethyl benzyl isocyanate, and acryloylethyl carbonic anhydride. In some embodiments the X—Z compound isisocyanatoethyl methacrylate or vinyl dimethyl azlactone.

In some embodiments the non-silicone urea-based diamine is reacted withan isocyanate functional (meth)acrylate as shown in reaction scheme IIbelow in which the R¹ group is an alkylene linking group such as a—CH₂CH₂— group and n is an integer of 30-40:

In some embodiments the non-silicone urea-based diamine is reacted withan azlactone as shown in reaction scheme III below in which the R²groups are alkyl groups such as methyl groups and n is as previouslydefined:

A second reaction pathway to obtain the non-silicone urea-based reactiveoligomers of this disclosure involves a two step reaction sequence. Inthe first step a non-silicone urea-based diamine is capped with adifunctional Z—W—Z compound. The Z groups of the Z—W—Z compound areamine reactive groups. A variety of Z groups are useful for thisreaction pathway including carboxylic acids, isocyantes, epoxies, andazlactones. Typically Z is an isocyanate. The W group of the Z—W—Zcompound is a linking group that links the Z groups. The W group may bean alkylene group, a heteroalkylene group, an arylene group, aheteroarylene group, an aralkylene group, or a combination thereof

Examples of useful Z—W—Z compounds are diisocyanates. Examples of suchdiisocyanates include, but are not limited to, aromatic diisocyanates,such as 2,6-toluene diisocyanate, 2,5-toluene diisocyanate, 2,4-toluenediisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate,methylene bis(o-chlorophenyl diisocyanate),methylenediphenylene-4,4′-diisocyanate, polycarbodiimide-modifiedmethylenediphenylene diisocyanate,(4,4′-diisocyanato-3,3′,5,5′-tetraethyl) biphenylmethane,4,4′-diisocyanato-3,3′-dimethoxybiphenyl, 5-chloro-2,4-toluenediisocyanate, 1-chloromethyl-2,4-diisocyanato benzene,aromatic-aliphatic diisocyanates such as m-xylylene diisocyanate,tetramethyl-m-xylylene diisocyanate, aliphatic diisocyanates, such as1,4-diisocyanatobutane, 1,6-diisocyanatohexane,1,12-diisocyanatododecane, 2-methyl-1,5diisocyanatopentane, andcycloaliphatic diisocyanates such asmethylene-dicyclohexylene-4,4′-diisocyanate, and3-isocyanatomethyl-3,5,5-trimethyl-cyclohexyl isocyanate (isophoronediisocyanate).

Typically the Z—W—Z compound is an aliphatic or cycloaliphaticdiisocyanate such as 1,6-diisocyanatohexane or isophorone diisocyanate.

For example, a non-silicone urea-based diamine may be reacted with adiisocyanate to a generate a non-silicone urea-based diisocyanate. Thenon-silicone urea-based diisocyanate can then be further reacted with aY—X compound. The Y of the Y—X compound is an isocyanate reactive groupsuch as an alcohol, an amine or a mercaptan. Typically the Y group is analcohol. The X group contains an ethylenically unsaturated group (i.e. acarbon-carbon double bond) and is linked to the Y group. The linkbetween the X and Y groups may be a single bond or it may be a linkinggroup. The linking group may be an alkylene group, a heteroalkylenegroup, an arylene group, a heteroarylene group, an aralkylene group, ora combination thereof.

Examples of useful Y—X compounds include hydroxyl functional(meth)acrylates such as (meth)acrylic acid monoesters of polyhydroxyalkyl alcohols such as 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, the various butyl diols, the various hexanediols, glycerol, suchthat the resulting esters are referred to as hydroxyalkyl(meth)acrylates. In some embodiments, the Y—X compound is hydroxyl ethylacrylate.

In some embodiments the non-silicone urea-based diamine is reacted witha diisocyanate to form a non-silicone urea-based diisocyanate. Thisnon-silicone urea-based diisocyanate is then reacted with a hydroxylfunctional (meth)acrylate as shown in reaction scheme IV below in whichOCN—R³—NCO is isophorone diisocyanate and R⁴ is an alkylene linkinggroup such as a —CH₂CH₂— group, n is as previously defined, and thecatalyst is dibutyltin dilaurate:

Non-silicone urea-based pressure sensitive adhesives may be prepared bypolymerizing X—B—X reactive oligomers through the ethylenicallyunsaturated X groups to form polymers with adhesive properties. Thepolymers may contain only X—B—X reactive oligomers or they may becopolymers in which additional monomers or reactive oligomers areincorporated. As used herein, additional monomers or reactive oligomersare collectively referred to as ethylenically unsaturated materials.

Among the additional monomers useful for incorporation are monomerswhich contain ethylenically unsaturated groups and are thereforeco-reactive with the reactive oligomers. Examples of such monomersinclude (meth)acrylates, (meth)acrylamides, alpha-olefins, and vinylcompounds such as vinyl acids, acrylonitriles, vinyl esters, vinylethers, styrenes and ethylenically unsaturated oligomers. In someinstances more than one type of additional monomer may be used.

Examples of useful (meth)acrylates include alkyl (meth)acrylates,aromatic (meth)acrylates, and silicone acrylates. In applications inwhich it is desirable that the entire adhesive composition be siliconefree, silicone acrylates are generally not used. Alkyl (meth)acrylatemonomers are those in which the alkyl groups comprise 1 to about 20carbon atoms (e.g., from 3 to 18 carbon atoms). Suitable acrylatemonomers include, for example, methyl acrylate, ethyl acrylate, n-butylacrylate, lauryl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate,iso-octyl acrylate, octadecyl acrylate, nonyl acrylate, decyl acrylate,and dodecyl acrylate. The corresponding methacrylates are useful aswell. An example of an aromatic (meth)acrylate is benzyl acrylate.

Examples of useful (meth)acrylamides, include acrylamide, methacrylamideand substituted (meth)acrylamides such as N,N-dimethyl acrylamide,N,N-dimethyl methacrylamide, N,N-dimethylaminopropyl methacrylamide,N,N-diethylaminopropyl methacrylamide. N,N-dimethylaminoethylacrylamide, N,N-dimethylaminoethyl methacrylamide, N,N-diethylaminoethylacrylamide, and N,N-diethylaminoethyl methacrylamide.

The alpha-olefins useful as additional monomers generally include thosewith 6 or greater carbon atoms. The alpha-olefins with fewer than 6carbon atoms tend to be too volatile for convenient handling underambient reaction conditions. Suitable alpha-olefins include, forexample, 1-hexene, 1-octene, 1-decene and the like.

Examples of useful vinyl compounds include: vinyl acids such as acrylicacid, itaconic acid, methacrylic acid; acrylonitriles such asacrylonitrile and methacrylonitrile; vinyl esters such as vinyl acetateand the vinyl esters of carboxylic acids such as neodecanoic,neononanoic, neopentanoic, 2-ethylhexanoic, or propionic acids; vinylethers such as alkyl vinyl ethers; and styrenes such as styrene or vinyltoluene. Other vinyl compounds that may be useful includeN-vinylcaprolactam, vinylidene chloride, N-vinyl pyrrolidone, N-vinylformamide, and maleic anhydride. For some uses, for example electronicapplications, it may be desirable to include vinyl compounds that arefree of acidic groups.

Examples of ethylenically unsaturated oligomers useful forcopolymerization with the urea-based reactive oligomers include, forexample, ethylenically unsaturated silicone oligomers such as aredescribe in the PCT publication number WO 94/20583 and macromolecularmonomers with relatively high glass transition temperatures as describedin U.S. Pat. No. 4,554,324 (Husman et al.). In applications in which itis desirable that the entire adhesive composition be silicone free,silicone oligomers are generally not used.

The non-silicone urea-based adhesives can be made by solvent processes,solventless processes (e.g., continuous solventless processes orpolymerization on a surface or in a mold) or by a combination of thesemethods.

Some of the processes suitable for the preparation of the non-siliconeurea-based adhesives include the free radical polymerization ofnon-silicone urea-based reactive oligomers with optional ethylenicallyunsaturated materials in a reactor to form the non-silicone urea-basedadhesive. The non-silicone urea-based adhesive can then be removed fromthe reaction vessel. Alternatively, the polymerization can be carriedout by continuously mixing the reactants and depositing the reactants ona surface (e.g., release liner or substrate) or into a mold andpolymerizing the mixture in place.

In some embodiments, it has been found convenient to deposit a mixtureof the non-silicone urea-based reactive oligomer, additional monomers ifdesired, and initiator onto a surface, activate the initiator and curethe adhesive on the surface. The mixture may or may not contain asolvent. If solvent is used, the cured adhesive is typically dried toremove the solvent.

The initiator may be either a thermal initiator or a photoinitiator.Suitable thermal free radical initiators which may be utilized include,but are not limited to, those selected from azo compounds, such as2,2′-azobis(isobutyronitrile); hydroperoxides, such as tert-butylhydroperoxide; and, peroxides, such as benzoyl peroxide andcyclohexanone peroxide. Photoinitiators which are useful include, butare not limited to, those selected from benzoin ethers, such as benzoinmethyl ether or benzoin isopropyl ether; substituted benzoin ethers,such as anisole methyl ether; substituted acetophenones, such as2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenyl acetophenone;substituted alpha-ketols, such as 2-methyl-2-hydroxy propiophenone;aromatic sulfonyl chlorides, such as 2-naphthalene sulfonyl chloride;and, photoactive oximes, such as1-phenyl-1,2-propanedione-2-(ethoxycarbonyl)oxime. For both thermal- andradiation-induced polymerizations, the initiator is present in an amountof about 0.05% to about 5.0% by weight based upon the total weight ofthe monomers.

In addition to the reactants, optional property modifying additives canbe mixed with the reactive oligomers and optional other monomersprovided that they do not interfere with the polymerization reaction.Typical property modifiers include tackifying agents (tackifiers) andplasticizing agents (plasticizers) to modify the adhesive performance ofthe formed adhesive composition. If used, the tackifiers andplasticizers are generally present in amounts ranging from about 15% toabout 45% by weight, or even from about 15% to about 35% by weight.

Useful tackifiers and plasticizers are those conventionally used in theadhesive arts. Examples of suitable tackifying resins include terpenephenolics, alpha methyl styrene resins, rosin derived tackifiers,monomeric alcohols, oligomeric alcohols, oligomeric glycols, andmixtures thereof. Examples of useful plasticizing resins include terpenephenolics, rosin derived plasticizers, polyglycols and mixtures thereof.In some embodiments the plasticizer is isopropyl myristate or apolypropylene glycol.

In addition, other property modifiers, such as fillers, may be added ifdesired, provided that if and when incorporated, such additives are notdetrimental to the properties desired in the final composition. Fillers,such as fumed silica, fibers (e.g., glass, metal, inorganic, or organicfibers), carbon black, glass or ceramic beads/bubbles, particles (e.g.,metal, inorganic, or organic particles), polyaramids (e.g., thoseavailable from DuPont Chemical Company; Wilmington, Del. under the tradedesignation, KEVLAR), and the like which can be added in amounts up toabout 30% by weight. Other additives such as dyes, inert fluids (e.g.,hydrocarbon oils), pigments, flame retardants, stabilizers,antioxidants, compatibilizers, antimicrobial agents (e.g., zinc oxide),electrical conductors, thermal conductors (e.g., aluminum oxide, boronnitride, aluminum nitride, and nickel particles), and the like can beblended into these systems in amounts of generally from about 1 to about50 percent by total volume of the composition.

The adhesives formed by the polymerization of the non-siliconeurea-based reactive oligomers may be pressure sensitive adhesives orheat activated adhesives. Generally pressure sensitive adhesives areformed. These pressure sensitive adhesives are useful in a wide array ofapplications.

The use of reactive oligomers instead of low molecular weight monomersto generate the pressure sensitive adhesive polymers results in polymersthat are free of volatile unreacted materials and other low molecularweight impurities after polymerization. Residual monomers and lowmolecular weight impurities may be problematic in certain applications,such as medical and electronic applications. In medical and electronicapplications, residual monomers and impurities may cause, for example,undesirable odor or potential contamination of substrates/articles(e.g., hard disk drives) in which they are in contact. In addition, theuse of reactive oligomers which are free of silicone is desirable incertain industries, such as the electronics industry, where siliconecontamination is a concern.

The adhesive, or the reactive mixture which upon polymerization formsthe adhesive, may be coated onto a surface to form a wide variety ofadhesive articles. For example, the adhesive can be applied to films orsheeting products (e.g., decorative, reflective, and graphical),labelstock, tape backings, release liners, and the like. The substratecan be any suitable type of material depending on the desiredapplication.

The adhesive can be formed into a film or coating by either continuousor batch processes. An example of a batch process is the placement of aportion of the adhesive between a substrate to which the film or coatingis to be adhered and a surface capable of releasing the adhesive film orcoating to form a composite structure. The composite structure can thenbe compressed at a sufficient temperature and pressure to form aadhesive coating or film of a desired thickness after cooling.Alternatively, the adhesive can be compressed between two releasesurfaces and cooled to form an adhesive transfer tape useful inlaminating applications.

Continuous forming methods include drawing the adhesive out of a filmdie and subsequently contacting the drawn adhesive to a moving plasticweb or other suitable substrate. A related continuous method involvesextruding the adhesive and a coextruded backing material from a film dieand cooling the layered product to form an adhesive tape. Othercontinuous forming methods involve directly contacting the adhesive to arapidly moving plastic web or other suitable preformed substrate. Usingthis method, the adhesive is applied to the moving preformed web using adie having flexible die lips, such as a rotary rod die. After forming byany of these continuous methods, the adhesive films or layers can besolidified by quenching using both direct methods (e.g., chill rolls orwater baths) and indirect methods (e.g., air or gas impingement).

Adhesives can also be coated using a solvent-based method. For example,the adhesive can be coated by such methods as knife coating, rollcoating, gravure coating, rod coating, curtain coating, and air knifecoating. The adhesive mixture may also be printed by known methods suchas screen printing or inkjet printing. The coated solvent-based adhesiveis then dried to remove the solvent. Typically, the coated solvent-basedadhesive is subjected to elevated temperatures, such as those suppliedby an oven, to expedite drying of the adhesive.

In some embodiments it may be desirable to impart a microstructuredsurface to one or both major surfaces of the adhesive. It may bedesirable to have a microstructured surface on at least one surface ofthe adhesive to aid air egress during lamination. If it is desired tohave a microstructured surface on one or both surfaces of the adhesivelayer, the adhesive coating or layer may be placed on a tool or a linercontaining microstructuring. The liner or tool can then be removed toexpose an adhesive layer having a microstructured surface.

The thickness of the adhesive layer tends to be at least about 1micrometer, at least 5 micrometers, at least 10 micrometers, at least 15micrometers, or at least 20 micrometers. The thickness is often nogreater than about 200 micrometers, no greater than about 175micrometers, no greater than about 150 micrometers, or no greater thanabout 125 micrometers. For example, the thickness can be 1 to 200micrometers, 5 to 100 micrometers, 10 to 50 micrometers, 20 to 50micrometers, or 1 to 15 micrometers.

In some embodiments, the pressure sensitive adhesives are opticallyclear. Optically clear adhesives may be used to make a wide array ofoptical articles. Such articles may include an optical film, a substrateor both. Such uses include information displays, window coverings,graphic articles and the like.

Articles are provided that include an optical film and a pressuresensitive adhesive layer adjacent to at least one major surface of theoptical film. The articles can further include another substrate (e.g.,permanently or temporarily attached to the pressure sensitive adhesivelayer), another adhesive layer, or a combination thereof. As usedherein, the term “adjacent” can be used to refer to two layers that arein direct contact or that are separated by one or more layers. Often,adjacent layers are in direct contact.

In some embodiments, the resulting articles can be optical elements orcan be used to prepare optical elements. As used herein, the term“optical element” refers to an article that has an optical effect oroptical application. The optical elements can be used, for example, inelectronic displays, architectural applications, transportationapplications, projection applications, photonics applications, andgraphics applications. Suitable optical elements include, but are notlimited to, screens or displays, cathode ray tubes, polarizers,reflectors, and the like.

Any suitable optical film can be used in the articles. As used herein,the term “optical film” refers to a film that can be used to produce anoptical effect. The optical films are typically polymer-containing filmsthat can be a single layer or multiple layers. The optical films areflexible and can be of any suitable thickness. The optical films oftenare at least partially transmissive, reflective, antireflective,polarizing, optically clear, or diffusive with respect to somewavelengths of the electromagnetic spectrum (e.g., wavelengths in thevisible ultraviolet, or infrared regions of the electromagneticspectrum). Exemplary optical films include, but are not limited to,visible mirror films, color mirror films, solar reflective films,infrared reflective films, ultraviolet reflective films, reflectivepolarizer films such as a brightness enhancement films and dualbrightness enhancement films, absorptive polarizer films, opticallyclear films, tinted films, and antireflective films.

In some embodiments the optical film has a coating. In general, coatingsare used to enhance the function of the film or provide additionalfunctionality to the film. Examples of coatings include, for example,hardcoats, anti-fog coatings, anti-scratch coatings, privacy coatings ora combination thereof. Coatings such as hardcoats, anti-fog coatings,and anti-scratch coatings that provide enhanced durability, aredesirable in applications such as, for example, touch screen sensors,display screens, graphics applications and the like. Examples of privacycoatings include, for example, blurry or hazy coatings to give obscuredviewing or louvered films to limit the viewing angle.

Some optical films have multiple layers such as multiple layers ofpolymer-containing materials (e.g., polymers with or without dyes) ormultiple layers of metal-containing material and polymeric materials.Some optical films have alternating layers of polymeric material withdifferent indexes of refraction. Other optical films have alternatingpolymeric layers and metal-containing layers. Exemplary optical filmsare described in the following patents: U.S. Pat. No. 6,049,419(Wheatley et al.); U.S. Pat. No. 5,223,465 (Wheatley et al.); U.S. Pat.No. 5,882,774 (Jonza et al.); U.S. Pat. No. 6,049,419 (Wheatley et al.);U.S. Pat. No. RE 34,605 (Schrenk et al.); U.S. Pat. No. 5,579,162(Bjornard et al.), and U.S. Pat. No. 5,360,659 (Arends et al.).

The substrate included in the article can contain polymeric materials,glass materials, ceramic materials, metal-containing materials (e.g.,metals or metal oxides), or a combination thereof. The substrate caninclude multiple layers of material such as a support layer, a primerlayer, a hard coat layer, a decorative design, and the like. Thesubstrate can be permanently or temporarily attached to an adhesivelayer. For example, a release liner can be temporarily attached and thenremoved for attachment of the adhesive layer to another substrate.

The substrate can have a variety of functions such as, for example,providing flexibility, rigidity, strength or support, reflectivity,antireflectivity, polarization, or transmissivity (e.g., selective withrespect to different wavelengths). That is, the substrate can beflexible or rigid; reflective or non-reflective; visibly clear, coloredbut transmissive, or opaque (e.g., not transmissive); and polarizing ornon-polarizing.

Exemplary substrates include, but are not limited to, the outer surfaceof an electronic display such as liquid crystal display or a cathode raytube, the outer surface of a window or glazing, the outer surface of anoptical component such as a reflector, polarizer, diffraction grating,mirror, or lens, another film such as a decorative film or anotheroptical film, or the like.

Representative examples of polymeric substrates include those thatcontain polycarbonates, polyesters (e.g., polyethylene terephthalatesand polyethylene naphthalates), polyurethanes, poly(meth)acrylates(e.g., polymethyl methacrylates), polyvinyl alcohols, polyolefins suchas polyethylenes and polypropylenes, polyvinyl chlorides, polyimides,cellulose triacetates, acrylonitrile-butadiene-styrene copolymers, andthe like.

In other embodiments, the substrate is a release liner. Any suitablerelease liner can be used. Exemplary release liners include thoseprepared from paper (e.g., Kraft paper) or polymeric material (e.g.,polyolefins such as polyethylene or polypropylene, ethylene vinylacetate, polyurethanes, polyesters such as polyethylene terephthalate,and the like). At least some release liners are coated with a layer of arelease agent such as a silicone-containing material or afluorocarbon-containing material. Exemplary release liners include, butare not limited to, liners commercially available from CP Film(Martinsville, Va.) under the trade designation “T-30” and “T-10” thathave a silicone release coating on polyethylene terephthalate film. Theliner can have a microstructure on its surface that is imparted to theadhesive to form a microstructure on the surface of the adhesive layer.The liner can then be removed to expose an adhesive layer having amicrostructured surface.

The release liner can be removed to adhere the optical film to anothersubstrate (i.e., removal of the release liner exposes a surface of anadhesive layer that subsequently can be bonded to another substratesurface).

In some embodiments the adhesives are self wetting and removable. Theadhesives exhibit great conformability permitting them to spontaneouslywet out substrates. The surface characteristics also permit theadhesives to be bonded and removed from the substrate repeatedly forrepositioning or reworking. The strong cohesive strength of theadhesives gives them structural integrity limiting cold flow and givingelevated temperature resistance in addition to permanent removability.In some embodiments the initial removability of an adhesive coatedarticle bonded to a glass substrate, as measured by the 90° PeelAdhesion test described in the Examples section below, is no greaterthan 2.9 Newtons/decimeter (75 grams per inch). Upon aging for one weekat room temperature the removability, as measured by the 90° PeelAdhesion test described in the Examples section below, is no more than7.7 Newtons/decimeter (200 grams per inch). In other embodiments, theremovability after aging for at least one week at room temperature, asmeasured by the 90° Peel Adhesion test described in the Examples sectionbelow, is no more than 15.4 (400 grams per inch), 7.7 Newtons/decimeter(200 grams per inch) or even 3.9 Newtons/decimeter (100 grams per inch).

Exemplary adhesive articles in which the self wetting and removabilityfeatures are especially important include, for example: large formatarticles such as graphic articles and protective films; and informationdisplay devices.

Large-format graphic articles or protective films typically include athin polymeric film backed by a pressure sensitive adhesive. Thesearticles may be difficult to handle and apply onto a surface of asubstrate. The large format article may be applied onto the surface of asubstrate by what is sometimes called a “wet” application process. Thewet application process involves spraying a liquid, typically awater/surfactant solution, onto the adhesive side of the large formatarticle, and optionally onto the substrate surface. The liquidtemporarily “detackifies” the pressure sensitive adhesive so theinstaller may handle, slide, and re-position the large format articleinto a desired position on the substrate surface. The liquid also allowsthe installer to pull the large format article apart if it sticks toitself or prematurely adheres to the surface of the substrate. Applyinga liquid to the adhesive may also improve the appearance of theinstalled large format article by providing a smooth, bubble freeappearance with good adhesion build on the surface of the substrate.

Examples of a large format protective films include window films such assolar control films, shatter protection films, decoration films and thelike. In some instances the film may be a multilayer film such as amultilayer IR film (i.e., an infrared reflecting film), such as amicrolayer film having selective transmissivity such as an opticallyclear but infrared reflecting film as described in U.S. Pat. No.5,360,659 (Arends et al.).

While the wet application process has been used successfully in manyinstances, it is a time consuming and messy process. A “dry” applicationprocess is generally desirable for installing large format graphicarticles. Adhesives that are self wetting and removable may be appliedwith a dry installation process. The articles are easily attached to alarge substrate because they are self wetting and yet they may be easilyremoved and repositioned as needed.

In other applications, such as information display devices, the wetapplication process cannot be used. Examples of information displaydevices include devices with a wide range of display area configurationsincluding liquid crystal displays, plasma displays, front and rearprojection displays, cathode ray tubes and signage. Such display areaconfigurations can be employed in a variety of portable and non-portableinformation display devices including personal digital assistants, cellphones, touch-sensitive screens, wrist watches, car navigation systems,global positioning systems, depth finders, calculators, electronicbooks, CD or DVD players, projection television screens, computermonitors, notebook computer displays, instrument gauges, instrumentpanel covers, signage such as graphic displays (including indoor andoutdoor graphics, bumper stickers, etc) reflective sheeting and thelike.

A wide variety of information display devices are in use, bothilluminated devices and non-illuminated devices. Many of these devicesutilize adhesive articles, such as adhesive coated films, as part oftheir construction. One adhesive article frequently used in informationdisplay devices is a protective film. Such films are frequently used oninformation display devices that are frequently handled or have exposedviewing surfaces.

In some embodiments, the adhesives of this disclosure may be used toattach such films to information display devices because the adhesiveshave the properties of optical clarity, self wetting and removability.The adhesive property of optical clarity permits the information to beviewed through the adhesive without interference. The features of selfwetting and removability permit the film to be easily applied to displaysurface, removed and reworked if needed during assembly and also removedand replaced during the working life of the information display device.

EXAMPLES

These examples are merely for illustrative purposes only and are notmeant to be limiting on the scope of the appended claims. All parts,percentages, ratios, etc. in the examples and the rest of thespecification are by weight, unless noted otherwise. Solvents and otherreagents used were obtained from Sigma-Aldrich Chemical Company;Milwaukee, Wis. unless otherwise noted.

Table of Abbreviations Abbreviation or Trade Designation Description VDMvinyl dimethyl azlactone IEM isocyanatoethylmethacrylate IPDI Isophoronediisocyanate HEA Hydroxyethyl acrylate HCl Hydrochloric acid Polyamine-1Polyoxyalkylene polyamine of approximately 2,000 molecular weight,commercially available as “JEFFAMINE D-2000” from Huntsman, Houston, TX.Photoinitiator-1 Photoinitiator “DAROCUR 1173” commercially availablefrom Ciba, Hawthorne, NY. Photoinitiator-2 Photoinitiator “DAROCUR 4265”commercially available from Ciba, Hawthorne, NY. PET UV-primed polyesterfilm of polyethylene terephthalate available under the trade name“Dupont 617” having a thickness of 127 micrometers (5 mils) or 51micrometers (2 mils) from Dupont Teijin Films, Richmond, VA. ReleaseLiner Polyester film of 51 micrometer thickness (2 mils) coated on oneside with silicone release agent, commercially available from CP Film,Martinsville, VA as “T10 Release Liner”. UBDA 8K Urea-based diamine ofapproximately 8,000 molecular weight, prepared as described in SynthesisExample 1. UBDA 12K Urea-based diamine of approximately 12,000 molecularweight, prepared as described in Synthesis Example 2. AcAmine Acrylateddiamine prepared as described in Synthesis Example 3. IPM Isopropylmyristate PPG Polypropylene glycol of 3,000 molecular weight

Test Methods 90° Peel Adhesion

Adhesive coatings of 51 micrometers (2 mils) thickness on 51 micrometer(2 mil) thick PET film were cut into 2.54 centimeter by 15 centimeterstrips. Each strip was then adhered to a 6.2 centimeter by 23 centimeterclean, solvent washed glass coupon using a 2-kilogram roller passed onceover the strip. The bonded assembly dwelled at room temperature forabout one minute and was tested for 90° peel adhesion using an IMASSslip/peel tester with a 90° peel testing assembly (Model SP2000,commercially available from Instrumentors Inc., Strongsville, Ohio) at arate of 2.3 meters/minute (90 inches/minute) over a five second datacollection time. Three samples were tested; the reported peel adhesionvalue is an average of the peel adhesion value from each of the threesamples. Data was measured in grams/inch width and converted to Newtonsper decimeter (N/dm).

Wet Out Test

Adhesive coatings of 51 micrometers (2 mils) thickness on 127 micrometer(5 mil) thick PET film were cut into sample squares of 12.7 by 12.7centimeters (5 by 5 inches). A 7.6 by 7.6 centimeter (3 by 3 inch)square was marked in the center of the backside of each sample square.The liner was removed from the sample square and one corner of thesample square was placed on the surface of an isopropanol-washed glasscoupon. The sample square was dropped onto the glass surface. The wetout time was measured using a stopwatch and was started when the wet outfront reached any part of the inner marked square and ended when theinner square was completely wet out. The wet out time was recorded, andis reported as the time (in seconds) per area wet out (in squarecentimeters).

Titration Method to Determine Molecular Weight

To determine the molecular weight of a synthesized UBDA, a measuredsample weight (about 4-6 grams) was placed in a jar and tetrahydrofuran(about 3 times the weight of the sample) was added with mixing to form auniform solution. A solution of the indicator bromophenol blue was addeduntil the color was a deep blue. With constant stirring, the samplesolution was titrated by adding 1.0 Normal HCl (aq) dropwise until acolor change from blue to yellow indicated that the endpoint wasreached. The endpoint volume of HCl titrated was recorded and themolecular weight was calculated.

SYNTHESIS EXAMPLES Synthesis Example 1 Preparation of UBDA 8K

A sample of Polyamine-1 (4 moles) was degassed under vacuum at 100° C.for 1 hour. Freshly ground diphenyl carbonate (3 moles) was added andthe mixture stirred to give a uniform mixture. The mixture was heated to160° C. for 3 hours under vacuum to remove phenol byproduct. Theresultant product was a urea chain extended diamine of approximately8,000 molecular weight (confirmed by titration, using the methoddescribed above).

Synthesis Example 2 Preparation of UBDA 12K

A sample of Polyamine-1 (6 moles) was reacted with a sample of diphenylcarbonate (5 moles) using the procedure described in Synthesis Example 1above. The resultant product was a urea chain extended diamine ofapproximately 12,000 molecular weight (confirmed by titration, using themethod described above).

Synthesis Example 3 Preparation of AcAmine

A sample of Polyamine-1 (1 mole) was mixed with a sample of VDM (2moles) and permitted to react overnight with stirring.

Example 1

To a stirred sample of UBDA 8K (1 mole) was added slowly a sample of VDM(2 moles) at room temperature. The mixture was stirred and allowed toreact overnight. A sample of Photoinitiator-1 was added (0.5% byweight). The resultant mixture was cast between PET and a Release Lineron a knife die and marble bed hand spread coater to a thicknessappropriate for the test to be run on the sample and cured under highintensity UV exposure using a Fusion UV lamp from Fusion UV Systems,Inc. with an output of 600 W/inch (236 W/cm) and with a belt speed of 20feet per minute (6 meters per minute). Wet out testing to glass, 90°Peel adhesion to glass (initial and after aging for 1 week at 70° C.)were carried out using the test methods described above. The results arepresented in Table 1.

Example 2

To a stirred sample of UBDA 8K (1 mole) was added slowly a sample of IEM(2 moles) at room temperature. The mixture was stirred and allowed toreact overnight. A sample of Photoinitiator-1 was added (0.5% byweight). The resultant mixture was cast between PET and a Release Lineron a knife die and marble bed hand spread coater to a thicknessappropriate for the test to be run on the sample and cured under lowintensity UV exposure using 40 Watt, 350 nanometer bulbs for 10 minutes.Wet out testing to glass, 90° Peel adhesion to glass (initial and afteraging for 1 week at 70° C.) were carried out using the test methodsdescribed above. The results are presented in Table 1.

Example 3

To a stirred sample of UBDA 12K (1 mole) was added slowly a sample ofVDM (2 moles) at room temperature. The mixture was stirred and allowedto react overnight. A sample of Photoinitiator-1 was added (0.5% byweight). The resultant mixture was cast between PET and a Release Lineron a knife die and marble bed hand spread coater to a thicknessappropriate for the test to be run on the sample and cured under lowintensity UV exposure using 40 Watt, 350 nanometer bulbs for 10 minutes.Wet out testing to glass, 90° Peel adhesion to glass (initial and afteraging for 1 week at 70° C.) were carried out using the test methodsdescribed above. The results are presented in Table 1.

Example 4

To a stirred sample of UBDA 12K (1 mole) was added slowly a sample ofIEM (2 moles) at room temperature. The mixture was stirred and allowedto react overnight. A sample of Photoinitiator-1 was added (0.5% byweight). The resultant mixture was cast between PET and a Release Lineron a knife die and marble bed hand spread coater to a thicknessappropriate for the test to be run on the sample and cured under lowintensity UV exposure using 40 Watt, 350 nanometer bulbs for 10 minutes.Wet out testing to glass, 90° Peel adhesion to glass (initial and afteraging for 1 week at 70° C.) were carried out using the test methodsdescribed above. The results are presented in Table 1.

Comparative Example C1

A sample of AcAmine and Photoinitiator-2 (0.5% by weight) was castbetween PET and a Release Liner on a knife die and marble bed handspread coater to a thickness appropriate for the test to be run on thesample and cured under high intensity UV exposure using a Fusion UV lampfrom Fusion UV Systems, Inc. with an output of 600 W/inch (236 W/cm) andwith a belt speed of 20 feet per minute (6 meters per minute). Wet outtesting to glass, 90° Peel adhesion to glass (initial and after agingfor 1 week at 70° C.) were carried out using the test methods describedabove. The results are presented in Table 1.

TABLE 1 Initial 90° 90° Peel from Glass Wet-out Peel from after aging toglass Glass 1-week 70° C. Speed Example (N/dm) (N/dm) (sec/cm²) 1 3.126.04 0.55 2 1.59 1.56 0.84 3 5.17 12.74 1.39 4 3.90 10.31 2.08 C1 0.310.39 0.24

Example 5

To a stirred sample of UBDA 8K (1 mole) was added slowly a sample ofIPDI (2 moles, 30% solids in toluene) at room temperature. The mixturewas stirred and allowed to react overnight. To this mixture was added asample of HEA (2 moles) and urethane catalyst dibutyltin dilaurate (0.5%by weight) and the mixture was stirred overnight. A sample ofPhotoinitiator-1 was added (0.5% by weight). The resultant mixture wascast between 127 micrometer thick PET and a Release Liner on a knife dieand marble bed hand spread coater to a thickness of 76 micrometers (3mils) and cured under low intensity UV exposure using 40 Watt, 350nanometer bulbs for 10 minutes.

Example 6

To a stirred sample of UBDA 8K (1 mole) was added slowly a sample of VDM(2 moles) at room temperature. The mixture was stirred and allowed toreact overnight. To this was added a sample of AcAmine to give a weightratio of VDM capped UBDA 8K:AcAmine of 75:25. A sample ofPhotoinitiator-2 was added (0.5% by weight). The resultant mixture wascast between PET and a Release Liner on a knife die and marble bed handspread coater to a thickness appropriate for the test to be run on thesample and cured under high intensity UV exposure using a Fusion UV lampfrom Fusion UV Systems, Inc. with an output of 600 W/inch (236 W/cm) andwith a belt speed of 20 feet per minute (6 meters per minute). Wet outtesting to glass, 90° Peel adhesion to glass (initial and after agingfor 1 week at 70° C.) were carried out using the test methods describedabove. The results are presented in Table 2.

Example 7

To a stirred sample of UBDA 8K (1 mole) was added slowly a sample of VDM(2 moles) at room temperature. The mixture was stirred and allowed toreact overnight. To this was added a sample of IPM to give a weightratio of VDM capped UBDA 8K:IPM of 75:25. A sample of Photoinitiator-2was added (0.5% by weight). The resultant mixture was cast between PETand a Release Liner on a knife die and marble bed hand spread coater toa thickness appropriate for the test to be run on the sample and curedunder high intensity UV exposure using a Fusion UV lamp from Fusion UVSystems, Inc. with an output of 600 W/inch (236 W/cm) and with a beltspeed of 20 feet per minute (6 meters per minute). Wet out testing toglass, 90° Peel adhesion to glass (initial and after aging for 1 week at70° C.) were carried out using the test methods described above. Theresults are presented in Table 2.

Example 8

To a stirred sample of UBDA 8K (1 mole) was added slowly a sample of VDM(2 moles) at room temperature. The mixture was stirred and allowed toreact overnight. To this was added a sample of PPG to give a weightratio of VDM capped UBDA 8K:PPG of 75:25. A sample of Photoinitiator-2was added (0.5% by weight). The resultant mixture was cast between PETand a Release Liner on a knife die and marble bed hand spread coater toa thickness appropriate for the test to be run on the sample and curedunder high intensity UV exposure using a Fusion UV lamp from Fusion UVSystems, Inc. with an output of 600 W/inch (236 W/cm) and with a beltspeed of 20 feet per minute (6 meters per minute). Wet out testing toglass, 90° Peel adhesion to glass (initial and after aging for 1 week at70° C.) were carried out using the test methods described above. Theresults are presented in Table 2.

TABLE 2 Initial 90° 90° Peel from Glass Wet-out Peel from after aging toglass Glass 1-week 70° C. Speed Example (N/dm) (N/dm) (sec/cm²) 1 3.126.04 0.55 6 1.85 4.47 0.39 7 1.42 3.31 0.08 8 6.97 7.28 0.32

Example 9

Samples were prepared as described in Example 1 above and extended agingtesting was carried out by 90° Peel adhesion to glass (initial and afteraging for 1 week at 70° C., 3 weeks at 70° C., and 6 weeks at 70° C.)were carried out using the test method described above. The results arepresented in Table 3.

TABLE 3 90° Peel Adhesion Aging Time at 70° C. (N/dm) Initial (0 hours)3.12 1 week (168 hours) 6.04 3 weeks (500 hours) 7.12 6 weeks (1000hours) 6.70

What is claimed is:
 1. An adhesive comprising a cured mixturecomprising: at least one X—B—X reactive oligomer, wherein X comprises anethylenically unsaturated group, and B comprises a non-siliconesegmented urea-based unit, wherein the X—B—X reactive oligomer is thereaction product of a non-silicone segmented urea-based diamine and aZ—W—Z material, wherein Z comprises an amine-reactive group and Wcomprises a linking group, followed by the reaction with a Y—X materialwherein X comprises an ethylenically unsaturated group, and Y comprisesa Z-reactive group, and wherein the non-silicone segmented urea-baseddiamine is the reaction product of a polyoxyalkylene diamine with adiaryl carbonate; and an initiator, wherein the adhesive is a pressuresensitive adhesive.
 2. The adhesive of claim 1, wherein Z—W—Z comprisesa diisocyanate and Y—X comprises a hydroxyl-functional (meth)acrylate.3. The adhesive of claim 1, wherein the adhesive is a self-wetting andremovable adhesive.
 4. The adhesive of claim 1, wherein cured mixturefurther comprises an ethylenically unsaturated material.
 5. The adhesiveof claim 1, further comprising at least one additive, wherein theadditive comprises a pressure sensitive adhesive, a plasticizing agent,a tackifying agent or a mixture thereof.
 6. The adhesive of claim 5,comprising 5-60 weight % of added pressure sensitive adhesive and 5-55weight % plasticizer.
 7. The adhesive of claim 5, wherein theplasticizer comprises isopropyl myristate.
 8. The adhesive of claim 6,wherein the added pressure sensitive adhesive comprises a (meth)acrylatepressure sensitive adhesive.
 9. A polymerizable reactive oligomercomprising the structure X—B—X, wherein X comprises an ethylenicallyunsaturated group and B comprises a non-silicone segmented urea-basedunit.
 10. The reactive oligomer of claim 9, wherein the non-siliconesegmented urea-based unit comprises at least one urea group and at leastone oxyalkylene group.
 11. An adhesive comprising a cured reactionmixture, the reaction mixture comprising: at least one X—B—X reactiveoligomer, wherein X comprises an ethylenically unsaturated group, and Bcomprises a non-silicone segmented urea-based unit; and wherein theX—B—X reactive oligomer is the reaction product of a non-siliconesegmented urea-based diamine and a Z—X material, wherein X comprises anethylenically unsaturated group, and Z comprises an amine-reactivegroup, wherein the amine-reactive group Z reacts with an amine group ofthe non-silicone segmented urea-based diamine and wherein thenon-silicone segmented urea-based diamine is the reaction product of apolyoxyalkylene diamine with urea; and an initiator; and wherein theadhesive is a pressure sensitive adhesive or a heat activated adhesive.12. The adhesive of claim 11, wherein Z comprises an isocyanate, anazlactone, an anhydride or a combination thereof.
 13. The adhesive ofclaim 11, wherein the adhesive is a self-wetting and removable adhesive.14. The adhesive of claim 11, wherein the cured mixture furthercomprises an ethylenically unsaturated material.
 15. The adhesive ofclaim 11, further comprising an additive, wherein the additive comprisesa pressure sensitive adhesive, a plasticizing agent, a tackifying agentor mixture thereof.
 16. The adhesive of claim 15, comprising 5-60 weight% pressure sensitive adhesive and 5-55 weight % plasticizer.
 17. Theadhesive of claim 15, wherein the pressure sensitive adhesive comprisesan acid-containing (meth)acrylate pressure sensitive adhesive.
 18. Amethod of preparing an adhesive comprising: providing a curablecomposition comprising: at least one X—B—X reactive oligomer, wherein Xcomprises an ethylenically unsaturated group, and B comprises anon-silicone segmented urea-based unit, wherein the X—B—X reactiveoligomer is the reaction product of a non-silicone segmented urea-baseddiamine and a Z—W—Z material, wherein Z comprises an amine-reactivegroup and W comprises a linking group, followed by the reaction with aY—X material wherein X comprises an ethylenically unsaturated group, andY comprises an Z-reactive group, wherein Z—W—Z comprises a diisocyanateand Y—X comprises a hydroxyl-functional (meth)acrylate; and aninitiator; and curing the curable composition; wherein the adhesive is apressure sensitive adhesive.
 19. The method of claim 18, wherein thenon-silicone segmented urea-based diamine is the reaction product of apolyoxyalkylene diamine with a diaryl carbonate.
 20. The method of claim18, wherein the non-silicone segmented urea-based diamine is thereaction product of a polyoxyalkylene diamine with urea.
 21. An adhesivearticle comprising: a pressure sensitive adhesive comprising the curedreaction product of at least one X—B—X reactive oligomer, wherein Xcomprises an ethylenically unsaturated group, and B comprises anon-silicone segmented urea-based unit wherein the X—B—X reactiveoligomer is the reaction product of a non-silicone segmented urea-baseddiamine and a Z—X material, wherein X comprises an ethylenicallyunsaturated group, and Z comprises an amine-reactive group, wherein theamine-reactive group Z reacts with an amine group of the non-siliconesegmented urea-based diamine and wherein the non-silicone segmentedurea-based diamine is the reaction product of a polyoxyalkylene diaminewith urea; and a substrate.
 22. The adhesive article of claim 21,wherein the pressure sensitive adhesive further comprises at least oneadditive, wherein the additive comprises a pressure sensitive adhesive,a plasticizing agent, a tackifying agent, or a mixture thereof.
 23. Theadhesive article of claim 22, wherein additive pressure sensitiveadhesive comprises an acid-containing (meth)acrylate pressure sensitiveadhesive
 24. The adhesive article of claim 22, wherein the plasticizercomprises isopropyl myristate.
 25. The adhesive article of claim 21,wherein the substrate is a tape backing, a film, a sheet, or a releaseliner.